feat(pricing): add bare k3 alias for Kimi For Coding plan

The Kimi For Coding subscription reports its K3 model under the short
id `k3` (no `kimi-` prefix), whereas the regular Moonshot API still uses
the full `kimi-k3`. Seed a `k3` alias row right after `kimi-k3` at the
same official list price ($3/M in, $15/M out, $0.30/M cache read) so
coding-plan usage is priced correctly. Mirrors the existing
hunyuan-hy3/hy3 bare-alias precedent.

Pricing is matched by exact model id, so this does not touch the
`kimi-for-coding` endpoint alias (intentionally unpriced, subscription
semantics) nor risk prefix mismatches. Seed-only, no schema bump.

src-tauri/src/database/schema.rs

@@ -2100,6 +2100,8 @@ impl Database {
                 "0",
             ),
             ("kimi-k3", "Kimi K3", "3.00", "15.00", "0.30", "0"),
+            // Kimi For Coding 套餐里 K3 的裸名（无 kimi- 前缀），同标准 list 价
+            ("k3", "Kimi K3", "3.00", "15.00", "0.30", "0"),
             // 腾讯混元 (Tencent Hunyuan)（官方 CNY 1/4/0.25 按 1 USD ≈ 7.14 折算；Hy3 阶梯计价取最低档）
             ("hunyuan-hy3", "Hunyuan Hy3", "0.14", "0.56", "0.035", "0"),
             ("hy3", "Hunyuan Hy3", "0.14", "0.56", "0.035", "0"),